BMC Microbiology BioMed Central Review Protein secretion systems in bacterial-host associations, and their description in the Gene Ontology

Virginia Bioinformatics Institute, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
BMC Microbiology (Impact Factor: 2.98). 02/2009; 9 Suppl 1(Suppl 1):S2. DOI: 10.1186/1471-2180-9-S1-S2
Source: PubMed

ABSTRACT Protein secretion plays a central role in modulating the interactions of bacteria with their environments. This is particularly the case when symbiotic bacteria (whether pathogenic, commensal or mutualistic) are interacting with larger host organisms. In the case of Gram-negative bacteria, secretion requires translocation across the outer as well as the inner membrane, and a diversity of molecular machines have been elaborated for this purpose. A number of secreted proteins are destined to enter the host cell (effectors and toxins), and thus several secretion systems include apparatus to translocate proteins across the plasma membrane of the host also. The Plant-Associated Microbe Gene Ontology (PAMGO) Consortium has been developing standardized terms for describing biological processes and cellular components that play important roles in the interactions of microbes with plant and animal hosts, including the processes of bacterial secretion. Here we survey bacterial secretion systems known to modulate interactions with host organisms and describe Gene Ontology terms useful for describing the components and functions of these systems, and for capturing the similarities among the diverse systems.

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Available from: Joao Carlos Setubal, Aug 02, 2015
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    • "While growing either in a natural ecosystem or artificial conditions, bacteria secrete intracellular products into their extracellular milieu (Tseng et al. 2009). Secretory products are not only involved in bacterial social behavior , usually referred to as quorum sensing (Molloy 2010) but also in pathogenicity (Lee and Schneewind 2001) and inter-kingdom communication (Hughes and Sperandio 2008; Shen et al. 2012; Furusawa et al. 2013). "
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    ABSTRACT: The secretion of biomolecules into the extracellular milieu is a common and well-conserved phenomenon in biology. In bacteria, secreted biomolecules are not only involved in intra-species communication but they also play roles in inter-kingdom exchanges and pathogenicity. To date, released products, such as small molecules, DNA, peptides, and proteins, have been well studied in bacteria. However, the bacterial extracellular RNA complement has so far not been comprehensively characterized. Here, we have analyzed, using a combination of physical characterization and high-throughput sequencing, the extracellular RNA complement of both outer membrane vesicle (OMV)-associated and OMV-free RNA of the enteric Gram-negative model bacterium Escherichia coli K-12 substrain MG1655 and have compared it to its intracellular RNA complement. Our results demonstrate that a large part of the extracellular RNA complement is in the size range between 15 and 40 nucleotides and is derived from specific intracellular RNAs. Furthermore, RNA is associated with OMVs and the relative abundances of RNA biotypes in the intracellular, OMV and OMV-free fractions are distinct. Apart from rRNA fragments, a significant portion of the extracellular RNA complement is composed of specific cleavage products of functionally important structural noncoding RNAs, including tRNAs, 4.5S RNA, 6S RNA, and tmRNA. In addition, the extracellular RNA pool includes RNA biotypes from cryptic prophages, intergenic, and coding regions, of which some are so far uncharacterised, for example, transcripts mapping to the fimA-fimL and ves-spy intergenic regions. Our study provides the first detailed characterization of the extracellular RNA complement of the enteric model bacterium E. coli. Analogous to findings in eukaryotes, our results suggest the selective export of specific RNA biotypes by E. coli, which in turn indicates a potential role for extracellular bacterial RNAs in intercellular communication.
    MicrobiologyOpen 01/2015; 4(2). DOI:10.1002/mbo3.235 · 2.21 Impact Factor
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    • "T6SS contributes to biofilm formation and seed-to-seedling transmission of Acidovorax citrulli on melon 3 et al., 2010 ; Blondel et al., 2010 ; Filloux et al. , 2008 ; Hsu et al . , 2009 ; Mattinen et al . , 2007 ; Records and Gross , 2010 ; Shrivastava and Mande , 2008 ; Tseng et al . , 2009 ; Wu et al . , 2008 ; Zheng and Leung , 2007 ) . However , the exact mechanism of T6SS and the contribution of T6SS effectors to virulence remain to be elucidated . T6SSs are typically encoded by clusters of 12 to more than 20 genes ; however , the minimal number of genes needed to produce a functional apparatus is 13 ( Boyer et al . , "
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    ABSTRACT: The type VI protein secretion system (T6SS) is essential for virulence of several Gram-negative bacteria. In this study, we identified a T6SS gene cluster in Acidovorax citrulli, a plant pathogenic bacterium that causes bacterial fruit blotch (BFB) of cucurbits. One T6SS cluster, approximately 25 kb in length, and comprised of 17 genes was found in the A. citrulli AAC00-1 genome. Seventeen A. citrulli mutants were generated, each with a deletion of a single T6SS core gene. There were significant differences in BFB seed-to-seedling transmission between wild type A. citrulli strain, xjl12, and ΔvasD, ΔimpK, ΔimpJ or ΔimpF mutants (71.71%, 9.83%, 8.41%, 7.15%, 5.99% BFB disease index, respectively). In addition, we observed that these four mutants were reduced in melon seed colonization and biofilm formation; however, they were not affected in virulence when infiltrated into melon seedling tissues. There were no significant differences in BFB seed-to-seedling transmission, melon tissue colonization and biofilm formation between xjl12 and the other 13 T6SS mutants. Overall, our results indicate that the T6SS plays a role in seed-to-seedling transmission of BFB on melon.
    Molecular Plant Pathology 05/2014; 16(1). DOI:10.1111/mpp.12159 · 4.49 Impact Factor
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    • "Given that M. xanthus has over 400 predicted lipoproteins (Bhat et al., 2011), and that some transferred proteins contain type I signal peptides (Pathak and Wall, 2012), there are many other candidate proteins for OME. Because protein cargo transfer is relatively non-specific and OME occurs bidirectionally between cells (Fig. 2), OME is functionally distinct from other dedicated bacterial transport systems, for example conjugative systems and type III and VI secretion systems, which transfer specific molecules unidirectionally to target cells (Tseng et al., 2009; Hayes et al., 2010; Konovalova and Sogaard- Andersen, 2011). The mentioned reporter, SS OM-mCherry, is a fluorescent protein and along with fluorescent lipid markers, transfer of proteins or lipids can be monitored in live cells (Wei et al., 2011; Pathak et al., 2012a). "
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    ABSTRACT: Through cooperative interactions, bacteria can build multicellular communities. To ensure that productive interactions occur, bacteria must recognize their neighbours and respond accordingly. Molecular recognition between cells is thus a fundamental behaviour, and in bacteria important discoveries have been made. This MicroReview focuses on a recently described recognition system in myxobacteria that is governed by a polymorphic cell surface receptor called TraA. TraA regulates outer membrane exchange (OME), whereby myxobacterial cells transiently fuse their OMs to efficiently transfer proteins and lipids between cells. Unlike other transport systems, OME is rather indiscriminate in what OM goods are transferred. In contrast, the recognition of partnering cells is discriminatory and only occurs between cells that bear identical or closely related TraA proteins. Therefore TraA functions in kin recognition and, in turn, OME helps regulate social interactions between myxobacteria. Here, I discuss and speculate on the social and evolutionary implications of OME and suggest it helps to guide their transition from free-living cells into coherent and functional populations.
    Molecular Microbiology 11/2013; 91(2). DOI:10.1111/mmi.12450 · 5.03 Impact Factor
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